Question 1 :
A 150 kg car engine develops 500 W for each kg. What force does it exert in moving the car at a speed of $20 ms^{–1}?$

Question 2 :
The energy used in one hour at the rate of 1kW is called 1 kW h. TRUE OR FALSE?

Question 4 :
A wind-mill is lifting water from a well. Is it a work?

Question 5 :
A rocket is moving up with a velocity $\upsilon$. If the velocity of this rocket is suddenly tripled, what will be the ratio of two kinetic energies?

Question 6 :
A ball is dropped from a height of 10 m. If the energy of the ball reduces by 40% after striking the ground, how much high can the ball bounce back? $(g = 10 m s^{–2})$

Question 7 :
A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be ($g=10 ms^{-2}$)

Question 8 :
An object in motion possesses what is known as the kinetic energy of the object.

Question 9 :
Soni says that the acceleration in an object could be zero even when several forces are acting on it. State true or false.

Question 10 :
Kamali is preparing for examinations. She spends lot of time in studies. She reads lots of books. In common parlance, she is ‘working hard’. But is it really a work?

Question 11 :
A freely falling object eventually stops on reaching the ground. What happens to its kinetic energy?

Question 12 :
How many kilograms will a man working at the power of 100 W, be able to lift at constant speed of $1 ms^{–1}$ vertically? $(g = 10 ms^{–2})$

Question 13 :
Compare the power at which a butterfly of mass 1.0 g that flies upward at a rate of $0.5 ms^{–1}$ is moving upwards against the force of gravity. $(given g = 10 ms^{–2})$

Question 14 :
The kinetic energy possessed by an object of mass, m and moving with a uniform velocity, v is _______.

Question 15 :
What are the various energy transformations that occur when you are riding a bicycle?

Question 17 :
Let a constant force, F act on an object. Let the object be displaced through a distance, s in the direction of the force. Let W be the work done. So W = ?

Question 18 :
The relation connecting the initial velocity $\left(u\right)$ and final velocity $\left(v\right)$ of an object moving with a uniform acceleration a, and the displacement, s is__________.

Question 20 :
Can any object have momentum even if its mechanical energy is zero?

Question 21 :
The kinetic energy of an object of mass m moving with a velocity of 5 $\frac{m}{s}$ is 25 J. What will be its kinetic energy when its velocity is doubled?

Question 22 :
A donkey is carrying a load on its back. Is it a work?

Question 23 :
A certain household has consumed 250 units of energy during a month. How much energy is this in joules?

Question 24 :
An automobile engine propels a 1000 kg car (A) along a levelled road at a speed of $36 kmh^{–1}$.Now, suppose after travelling a distance of 200 m, this car collides with another stationary car (B) of same mass and comes to rest. Let its engine also stop at the same time. Now car (B) starts moving on the same level road without getting its engine started. Find the speed of the car (B) just after the collision.

Question 25 :
If the object is starting from its stationary position, that is, u = 0, then work done, W = ?

Question 26 :
An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and final points of the object lie on the same horizonta line. What is the work done by the force of gravity on th object

Question 27 :
An automobile engine propels a 1000 kg car along a levelled road at a speed of $36 kmh^{–1}$. Find the power if the opposing frictional force is 100 N.

Question 28 :
The Jog Falls in Karnataka state are nearly 20 m high. 2000 tonnes of water falls from it in a minute. Calculate the equivalent power if all this energy can be utilized? $(g = 10 ms^{–2})$

Question 29 :
Can any object have mechanical energy even if its momentum is zero?

Question 30 :
A mass of 10 kg is at a point A on a table. It is moved to a point B. If the line joining A and B is horizontal, what is the work done on the object by the gravitational force?